Conventional turbine rotors made of Cr-Mo-V steel enable steam temperatures of about 550.degree. C. to be used.
In order to use steam at higher temperatures while retaining good mechanical properties, steels which are highly alloyed with chromium have been used, as described, for example, in published French Pat. No. 1 407 452.
Steel in accordance with the invention improves the mechanical properties both at ambient temperature and when hot, and may be used with steam at 600.degree. C.